fix: preserve "default" name for anonymous default exports with keepNames #7151

Copilot · 2025-11-20T09:09:56Z

Anonymous default export functions and classes lose their "default" name property even when output.keepNames is enabled, getting mangled names like dep_default instead.

Changes

module_finalizers/mod.rs: Insert __name helper calls for anonymous default exports when keepNames is enabled
module_finalizers/impl_visit_mut.rs: Process keep_name_statement_to_insert in visit_program to handle top-level declarations
tests: Add coverage for anonymous default export functions and classes

Example

Before:

// bundled output
function dep_default() {}
console.log(dep_default.name); // "dep_default"

After:

// bundled output
function dep_default() {}
__name(dep_default, "default");
console.log(dep_default.name); // "default"

Aligns with esbuild behavior for keepNames.

Original prompt

This section details on the original issue you should resolve

<issue_title>[Bug]: the name property of an anonymous default export function is not kept even if output.keepNames is enabled</issue_title>
<issue_description>### Reproduction link or steps

REPL

What is expected?

Running the bundled code outputs default.

What is actually happening?

Running the bundled code outputs dep_default.

System Info
REPL 1.0.0-beta.51
Any additional comments?

esbuild supports this correctly (esbuild try).

The same issue exists with classes (REPL).</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes [Bug]: the name property of an anonymous default export function is not kept even if output.keepNames is enabled #7150

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graphite-app · 2025-11-20T09:10:03Z

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IWANABETHATGUY · 2025-11-20T09:53:20Z

fix: preserve "default" name for anonymous default exports with keepNames #7151 👈 (View in Graphite)
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Co-authored-by: IWANABETHATGUY <[email protected]>

github-actions · 2025-11-20T10:08:08Z

Benchmarks Rust

target: main(53599b0)
pr: copilot/fix-anonymous-function-names(f154a21)

group                                                        pr                                     target
-----                                                        --                                     ------
bundle/bundle@multi-duplicated-top-level-symbol              1.00     61.9±1.59ms        ? ?/sec    1.00     61.8±1.88ms        ? ?/sec
bundle/bundle@multi-duplicated-top-level-symbol-sourcemap    1.00     67.9±1.01ms        ? ?/sec    1.01     68.3±1.18ms        ? ?/sec
bundle/bundle@rome_ts                                        1.00    104.7±1.50ms        ? ?/sec    1.01    105.3±1.54ms        ? ?/sec
bundle/bundle@rome_ts-sourcemap                              1.00    118.1±1.79ms        ? ?/sec    1.00    117.9±1.22ms        ? ?/sec
bundle/bundle@threejs                                        1.02     38.9±2.85ms        ? ?/sec    1.00     38.2±0.89ms        ? ?/sec
bundle/bundle@threejs-sourcemap                              1.00     41.8±0.62ms        ? ?/sec    1.00     42.0±0.59ms        ? ?/sec
bundle/bundle@threejs10x                                     1.00    383.8±3.95ms        ? ?/sec    1.00    384.0±4.16ms        ? ?/sec
bundle/bundle@threejs10x-sourcemap                           1.00    442.3±3.09ms        ? ?/sec    1.00    442.6±4.48ms        ? ?/sec
scan/scan@rome_ts                                            1.00     83.6±1.32ms        ? ?/sec    1.00     83.4±1.31ms        ? ?/sec
scan/scan@threejs                                            1.03     28.7±2.09ms        ? ?/sec    1.00     28.0±0.38ms        ? ?/sec
scan/scan@threejs10x                                         1.01    293.1±4.08ms        ? ?/sec    1.00    289.2±4.00ms        ? ?/sec

Copilot

Pull Request Overview

This PR fixes an issue where anonymous default export functions and classes lose their "default" name property when output.keepNames is enabled, instead getting mangled names like dep_default.

Key changes:

Adds __name() helper calls for anonymous default exports when keepNames is enabled
Refactors keep_name statement insertion logic into a reusable method
Adds test coverage for both anonymous default export functions and classes

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

File	Description
crates/rolldown/src/module_finalizers/mod.rs	Adds keep_name tracking for anonymous default exports and extracts insertion logic into `insert_keep_name_statements()`
crates/rolldown/src/module_finalizers/impl_visit_mut.rs	Refactors to use extracted `insert_keep_name_statements()` method and handles top-level declarations
crates/rolldown/tests/rolldown/issues/7150/*	Test files covering anonymous default export functions and classes with keepNames enabled
crates/rolldown/tests/snapshots/integration_rolldown__filename_with_hash.snap	Updated snapshot for new test case

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@shulaoda

## [1.0.0-beta.52] - 2025-11-26 💥 Breaking Change - Change `output.generatedCode.profilerNames` default to `false` 🔧 Vite-Style TypeScript Configuration - Rolldown now supports Vite-style automatic tsconfig resolution. Use `tsconfig: true` to enable auto-discovery mode where each module finds its nearest `tsconfig.json`. See more details [here](https://rolldown.rs/options/tsconfig) ⚙️ Upgraded to oxc v0.99.0 - Add `TSGlobalDeclaration` type - More details: https://github.com/oxc-project/oxc/releases/tag/crates_v0.99.0 ### 💥 BREAKING CHANGES - change `output.generatedCode.profilerNames` default to false (#7139) by @Copilot ### 🚀 Features - support vite-style tsconfig resolution (#6873) by @shulaoda - rolldown: oxc v0.99.0 (#7165) by @camc314 - browser: export `plugins` (#7210) by @sxzz - rolldown_plugin_vite_css_post: add `inline` parameter to `cssMinify` callback (#7191) by @shulaoda - rolldown_plugin_vite_build_import_analysis: implement `render_chunk` to replace `__VITE_IS_MODERN__` flag (#7178) by @shulaoda - rolldown_plugin_utils: optimize SVG data URL encoding (#7156) by @shulaoda - dev: replace `DevEngine::hasLatestBuildOutput` with `DevEngine::getBundleState` (#7145) by @sapphi-red - rolldown_plugin_vite_asset_import_meta_url: support `@vite-ignore` comment (#7141) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: implement static URL processing (#7140) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: align `asset_resolver` logic (#7137) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: align `try_fs_resolve` logic (#7136) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: validate relative paths (#7120) by @shulaoda - export `viteAssetImportMetaUrlPlugin` and add dynamic URL tests (#7119) by @shulaoda ### 🐛 Bug Fixes - watch overwrite rename event on linux (#7201) by @sapphi-red - preserve name for parenthesized anonymous default exports and arrow functions with keepNames (#7159) by @Copilot - rolldown_plugin_vite_html: add missing async attribute for inlined entry scripts (#7202) by @shulaoda - respect target setting in DCE to prevent modern syntax generation (#7128) by @Copilot - rolldown_plugin_vite_html: add semicolon to import statement in CSS removal (#7200) by @shulaoda - rolldown_plugin_vite_html: use correct CSS asset filename in HTML injection (#7199) by @shulaoda - rolldown_plugin_vite_css_post: handle scoped package names in lib CSS filename (#7198) by @shulaoda - rolldown_plugin_vite_html: use patched `html5gum` with correct span tracking (#7193) by @shulaoda - rolldown_plugin_vite_html: handle HTML strings in script tags correctly (#7192) by @shulaoda - handle JSON import namespace property access correctly (#7190) by @IWANABETHATGUY - only include runtime helpers from included modules (#7183) by @IWANABETHATGUY - rolldown_plugin_vite_html: normalize paths to use forward slashes in `original_file_name` (#7175) by @shulaoda - rolldown_plugin_vite_css_post: use `filename` instead of `reference_id` for imported assets (#7174) by @shulaoda - rolldown_plugin_vite_css_post: correct regex escaping in pure CSS chunk pruning (#7173) by @shulaoda - rolldown_plugin_vite_html: use correct dependency path for modulepreload links (#7172) by @shulaoda - update cur_stmt_index when processing top level statements (#7157) by @IWANABETHATGUY - rolldown_plugin_utils: strip leading character from public asset URL (#7170) by @shulaoda - rolldown_plugin_vite_html: use correct `public_base` for `html_result_map` key (#7169) by @shulaoda - rolldown_plugin_utils: correct runtime handling and escape single quotes in asset paths (#7168) by @shulaoda - rolldown_plugin_utils: prevent data race in `file_to_url` cache (#7166) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: correct glob pattern and query string handling in dynamic URLs (#7162) by @shulaoda - rolldown_plugin_vite_css_post: use correct start position in magic string updates (#7158) by @shulaoda - data race in `FileEmitter::emit_file` causing duplicate asset emissions (#7164) by @shulaoda - dev: watch files even if the build failed (#7149) by @sapphi-red - rolldown_plugin_utils: always use base64 encoding for data URLs (#7148) by @shulaoda - preserve "default" name for anonymous default exports with keepNames (#7151) by @Copilot - correctly handle cjs json module as entry point (#7147) by @IWANABETHATGUY - rolldown_plugin_utils: correct `reference_id` parsing in `render_asset_url_in_js` (#7143) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: exclude quotes from URL span (#7142) by @shulaoda - rolldown_plugin_vite_asset_import_meta_url: use template literal for glob result indexing (#7134) by @shulaoda - tree shake unused dynamic entry when `inlineDynamicImports` is enabled (#7129) by @IWANABETHATGUY - correct return value of `parse` / `parseSync` functions (#7127) by @sapphi-red ### 🚜 Refactor - rolldown_plugin_vite_transform: use `oxc_resolver` for tsconfig discovery (#7220) by @shulaoda - rolldown_plugin_vite_resolve: use `resolve_file` for tsconfig discovery (#7216) by @shulaoda - rolldown_plugin_utils: remove redundant `ViteMetadata::get_or_insert_default()` (#7189) by @shulaoda - rolldown_plugin_utils: simplify `ViteMetadata::get()` to always return a value (#7188) by @shulaoda - rolldown_utils: add `guess_mime_skip_utf8_check` for binary assets (#7161) by @shulaoda - rolldown_plugin_utils: extract asset URL parsing into `AssetUrlIter` (#7144) by @shulaoda - store pattern name in FilenameTemplate (#7132) by @IWANABETHATGUY ### 📚 Documentation - tsconfig: document auto-discovery mode and improve structure (#7228) by @shulaoda - add plugin hook filter compatibility and fallback guide (#7138) by @Copilot - update top level navigation (#7092) by @mdong1909 ### 🧪 Testing - add tsconfig include/exclude/files matching test cases (#6899) by @shulaoda - vite-tests: run `playwright install` in case playwright binary is missing (#7226) by @sapphi-red - watch: close watcher when an error occured in the test cases (#7225) by @sapphi-red - watch: reject `waitBuildFinished` if `ERROR` event occurs (#7224) by @sapphi-red ### ⚙️ Miscellaneous Tasks - example: revert accidental changes to basic-typescript (#7227) by @shulaoda - deps: update oxc apps (#7212) by @renovate[bot] - deps: update rust crates (#7204) by @renovate[bot] - deps: update `oxc_resolver_napi` to 11.14.0 (#7217) by @shulaoda - deps: update oxc_resolver (#6909) by @shulaoda - deps: update dependency glob to v13 (#7208) by @renovate[bot] - deps: update actions/checkout action to v6 (#7207) by @renovate[bot] - deps: update npm packages (#7206) by @renovate[bot] - deps: update github-actions (#7205) by @renovate[bot] - add missing status code comment (#7185) by @iiio2 - deps: update dependency oxlint-tsgolint to v0.8.1 (#7197) by @renovate[bot] - rust: add more tracing log for hmr + dev logic (#7179) by @hyf0 - deps: update dependency oxlint-tsgolint to v0.8.0 (#7167) by @renovate[bot] - deps: update dependency oxlint-tsgolint to v0.7.3 (#7133) by @renovate[bot] - merge similar inlineDynamicImports test case (#7131) by @IWANABETHATGUY - deps: update `rolldown-plugin-dts` to 0.18.0 (#7125) by @shulaoda Co-authored-by: shulaoda <[email protected]>

Copilot AI self-assigned this Nov 20, 2025

Initial plan

1216566

Copilot AI assigned IWANABETHATGUY Nov 20, 2025

Copilot started work on behalf of IWANABETHATGUY November 20, 2025 09:10 View session

Copilot AI and others added 3 commits November 20, 2025 09:23

Fix keepNames for anonymous default export functions and classes

8b5270b

Co-authored-by: IWANABETHATGUY <[email protected]>

Add test cases for anonymous default export keepNames

a6fc8a0

Co-authored-by: IWANABETHATGUY <[email protected]>

Apply linter fixes

614665d

Copilot AI changed the title ~~[WIP] Fix issue with anonymous default export function name retention~~ fix: preserve "default" name for anonymous default exports with keepNames Nov 20, 2025

Copilot finished work on behalf of IWANABETHATGUY November 20, 2025 09:39

Copilot AI requested a review from IWANABETHATGUY November 20, 2025 09:39

IWANABETHATGUY force-pushed the copilot/fix-anonymous-function-names branch from c0a82df to 80fdda4 Compare November 20, 2025 09:52

Fix Rust formatting (remove trailing whitespace)

1959f93

Co-authored-by: IWANABETHATGUY <[email protected]>

IWANABETHATGUY force-pushed the copilot/fix-anonymous-function-names branch from 80fdda4 to 1959f93 Compare November 20, 2025 10:08

feat: 🎸 update

f154a21

IWANABETHATGUY approved these changes Nov 20, 2025

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IWANABETHATGUY marked this pull request as ready for review November 20, 2025 10:14

Copilot AI review requested due to automatic review settings November 20, 2025 10:14

Copilot started reviewing on behalf of IWANABETHATGUY November 20, 2025 10:15 View session

Copilot finished reviewing on behalf of IWANABETHATGUY November 20, 2025 10:18

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IWANABETHATGUY requested review from hyf0 and sapphi-red November 20, 2025 12:11

sapphi-red approved these changes Nov 20, 2025

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IWANABETHATGUY merged commit 6ca52aa into main Nov 20, 2025
77 of 85 checks passed

IWANABETHATGUY deleted the copilot/fix-anonymous-function-names branch November 20, 2025 12:43

github-actions bot mentioned this pull request Nov 26, 2025

release: v1.0.0-beta.52 #7223

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github-actions bot mentioned this pull request Nov 26, 2025

release: v1.0.0-beta.52 #7229

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fix: preserve "default" name for anonymous default exports with keepNames #7151

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fix: preserve "default" name for anonymous default exports with keepNames #7151

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